Unsaturated polyester and epoxy-functional graded-rubber paint and process ii

ABSTRACT

A radiation-curable paint which on a pigment and particulate filler-free basis consists essentially of vinyl monomers and a unique, alpha-beta olefinically unsaturated, rubber-comprising resin formed by reacting a monohydroxy, monocarboxy terminated polyester with an acyl chloride to provide alpha-beta olefinic unsaturation and reacting the resultant alpha-beta olefinically unsaturated, monocarboxy terminated polyester with an epoxyfunctional, graded-rubber particle. The dispersion is applied to substrates as a paint film and cured thereon by exposure to ionizing radiation, e.g., an electron beam.

Unite States Patent Johnson et al.

[ Mar. 14, 1972 [54] UNSATURATED POLYESTER AND EPOXY-FUNCTIONAL GRADE!)-RUBBER PAINT AND PROCESS II [72] Inventors: Olin B. Johnson, Livonia;Santokh S.

Labana, Dearborn Heights, both of Mich.

[73] Assignce: Ford Motor Company, Dearborn, Mich.

[22] Filed: Dec. 21, I970 [21] Appl. No.1 100,460

[52] U.S.Cl. ..1l7/93.3l,260/78.3 UA, 260/835,

260/836, 260/859 R, 260/876 R, 260/881, 260/885, 260/886 [51] Int. ClC08g 45/14, C08g 45/04, C08f 15/00 [58] Field ofSearch..260/831,834,835,836,885, 260/859, 77.5 CR

[56] References Cited UNITED STATES PATENTS 3,423,481 1/1969 Mizutani..260/836 3,450,796 6/1969 Griffin ..260/885 3,502,745 3/1970 Minton..260/881 FOREIGN PATENTS OR APPLICATIONS 1,132,645 11/1968 GreatBritain ..260/836 Primary ExaminerPaul Lieberman Attorney-John R.Faulkner and Olin B. Johnson A radiation-curable paint which on apigment and particulate filler-free basis consists essentially of vinylmonomers and a unique, alpha-beta olefinically unsaturated,rubber-comprising resin formed by reacting a monohydroxy, monocarboxyterminated polyester with an acyl chloride to provide alphabeta olefinicunsaturation and reacting the resultant alphabeta olefinicallyunsaturated, monocarboxy terminated polyester with an epoxy-functional,graded-rubber particle. The dispersion is applied to substrates as apaint film and cured thereon by exposure to ionizing radiation, e.g., anelectron beam.

ABSTRACT 15 Claims, No Drawings UNSATURATED POLYESTER AND EPOXY-FUNCTIONAL GRADED-RUBBER PAINT AND PROCESS II THE INVENTION A unique,rubber-comprising, radiation-curable paint is provided by preparing afilm-forming dispersion of vinyl monomers and an alpha-beta olefinicallyunsaturated rubbercomprising resin formed by reacting an alpha-betaolefinically unsaturated, monocarboxy terminated polyester with an acylchloride and reacting the resultant alpha-beta olefinically unsaturated,monocarboxy terminated polyester with an epoxyfunctional graded-rubberparticle. The dispersion is applied to substrates, e.g., wood, metal,glass, shaped polymeric solid, etc, as a paint film and cured thereon byionizing radiation, preferably an electron beam having average energy inthe range of about 100,000 to about 500,000 electron volts.

1. The Polyester Reactant The alpha-beta olefinically unsaturatedmonocarboxylic acid terminated polyester used in the preparation of theresinous component of the paints herein advantageously have averagemolecular weight in the range of about 800 to about 3,000, commonly1,000 to 2,500. The polyester advantageously has about 0.5 to about 5,preferably about 0.7 to about 3.5 units of alpha-beta olefinicunsaturation per 1,000 units molecular weight.

These polyesters consist essentially of carbon, hydrogen and oxygen andcan be prepared by conventional methods for producing polyesters usingone or more monohydroxy, monocarboxy acids as the constituent monomers.Suitable hydroxy acids include, but not by way of limitation,lhydroxy-decanoic acid, l2-hydroxydodecanoic acid, 12- hydroxystearicacid, ricinoleic acid (l2-hydroxy-9-octadecanoic acid), and acids havingthe general structure R1?-RJCOOH where R, and R may be hydrogen or C toC alkyl groups and R is an alkyl or aromatic group containing one to 20carbon atoms.

The alpha-beta olefinic unsaturation of the polyester reacted with thegraded-rubber particle is provided by reacting the hydroxyl group of themonohydroxy, monocarboxy polyester prepolymer with an acyl chloride,e.g., acrylyl chloride or methacrylyl chloride.

ll. Preparation Of The Graded-Rubber Particle The graded-rubber particlehas a core of cross-linked, elastomeric, acrylic polymer, an outer shellcomprising methyl methacrylate and an epoxy-functional acrylate and anintermediate layer which is a copolymer of the monomers used to form thecore and the monomers used to form the outer shell.

The process for preparing these particulate materials is at least atwo-stage process. In one method of preparation, a major amount ofmonofunctional monoacrylate is emulsion copolymerized in the first stagewith a cross-linking amount of a dior tri-functional monomer containingtwo or more nonconjugated terminal ethylenic groups, preferably adiacrylate, using a water-soluble free radical initiator and a suitablesurfactant to yield a latex of relatively uniform particle size, e.g.,0.04 to 1 micron average diameter. Before this reaction reachessubstantial completion, i.e., when the reaction is between about 50 andabout 90, preferably between about 70 and about 89, percent complete,the second monomeric component, i.e., a mixture of about 65 to about 98,preferably about 70 to about 95, mole percent methyl methacrylate, andabout 2 to about 35, preferably about 5 to about 30 mole percent of anepoxy-functional acrylate, e.g., glycidyl methacrylate, or a mixture ofabout 2 to about 35, preferably about 5 to about 30 mole percentepoxy-functional acrylate and about 65 to about 98 mole percent of amonomer mixture selected from and consisting essentially of esters ofacrylic or methacrylic acid and a C -C monohydric alcohol, monovinylhydrocarbons, diacrylates and divinyl hydrocarbons, is added slowly tothe reaction mixture. The polymerization process is continued to yield astable latex of relatively uniform particle size and composition. Asurfactant is used in forming the emulsion and additional surfactant maybe added simultaneously with the second stage monomeric component.

The latex is coagulated, washed and dried to yield finely divided whitepowder suitable for use in this invention. Generally, the particles areprepared from monomers that will provide a cross-linked acrylic,rubberlike core and a glasslike polymeric outer shell at roomtemperature, e.g., 2030 C. The terms rubberlike and glasslike are, ofcourse, meaningless except when used in reference to a specifictemperature or temperature range. The particles should be formulated sothat the core retains its rubberlike properties and the outer shellretains its glasslike properties at temperatures encountered by articlesof commerce in the intended field of use. Hence, for practical purposes,the monomers should be selected so that the core has a glass transitiontemperature that is substantially below that of the outer shell.Advantageously, the difference in glass transition temperature betweenthe core and the shell is at least 50 C., preferably above 100C.

The core is formed from a major amount of an alkyl, monofunctional,monoacrylate and a cross-linking amount of a dior tri-functional monomercontaining two or more nonconjugated terminal ethylenic groups. Themonofunctional, alkyl, monoacrylate is preferably an ester of a C Cmonohydric alcohol and acrylic acid, e.g., ethyl acrylate, butylacrylate, hexyl acrylate, 2-ethyl hexyl acrylate and/or mixtures of thesame. Certain other alkyl acrylates may be used when the cross-linkedpolymer thereof has an appropriate glass transition temperature, e.g.,dodecyl methacrylate. Butyl acrylate and 2-ethyl hexyl acrylate are themost preferred of the monoacrylates for use in forming the core. Thepolymers produced from most methacrylates have glass transitiontemperatures which are too high to provide rubberlike properties atnormally encountered temperatures. Hence, except for special useapplications, the monoacrylate component of the core will be either anester (or esters) of acrylic acid or a mixture of a major amount of thesame and a minor amount of methacrylate.

Suitable cross-linking agents include, but not by way of limitation,1,3-butylene diacrylate, 1,3-butylene dimethacrylate, divinyl benzene,l,6-hexamehtylene diacrylate, 1,6 hexamethylene dimethacrylate, 1,1, l-trimethylolpropane trimethacrylate, 1,4-dimethylolcyclohexanedimethacrylate, allyl methacrylate, methallyl acrylate, methallylmethacrylate, diallyl maleate, diallyl fumarate, and diallyl phthalate.In one embodiment, the cross-linking agent is a diester of acrylic ormethacrylic acid and a C -C preferably C C dihydric alcohol. In anotherembodiment, the cross-linking agent is a triester of acrylic ormethacrylic acid and a C -C preferably C2-C6, trihydri c a lco hol.

In the first reaction stage, there is preferably employed about to about98 mole percent of a monofunctional, monoacrylate and about 20 to about2 mole percent of the cross-linking agent.

In the second stage reaction, it is preferred to use a mixture of about65 to about 98, preferably about 70 to about 95 percent methylmethacrylate and about 2 to about 35 preferably about 5 to about 30,mole percent of epoxy-functional acrylate. These are added before thefirst reaction ceases. The amounts of the second stage reactantsrelative to the combined first stage reactants may vary widely dependingupon the physical properties desired in the final product, i.e., fromabout 10 to about to about 90 to about 10 weight percent.

The methyl methacrylate concentration in the outer shell is advisedly atleast about 30 mole percent with he balance of the monofunctionalcomponent being made up of monofunctional monoacrylates, e.g., esters ofC -C monohydric alcohols and either acrylic or methacrylic acid, ormonofunctional vinyl hydrocarbons such as styrene, methyl substitutedstyrenes, e.g., alpha methyl styrene, vinyl toluene, etc. It will alsobe advantageous at times to have a limited amount of cross-linking inthe outer shell and hence to include in said balance" a minor amount ofa diacrylate, e.g., l to 30 mole percent ofa diester of acrylic ormethacrylic acid and a C -C preferably C -C dihydric alcohol, or divinylhydrocarbon, e.g., l to 30 mole percent of divinyl benzene. The physicalproperties ofthe outer shell may also be modified by replacing up toabout 30 mole percent of the methyl methacrylate with acrylonitrile ormethacrylonitrile.

The initial monomer charge is usually emulsified by one or moremicell-forming compounds composed of a hydrophobic part, such as ahydrocarbon group containing eight or more carbon atoms, and ahydrophilic part, such as alkaline metal or ammonium carboxylate groups,phosphate or sulfate partial ester groups, sulfonate groups, and thelike period. Exemplary emulsifying agents include alkali metalsulfonates of styrene, naphthalene, decyl benzene and dodecyl benzene;sodium dodecyl sulfate; sodium stearate; sodium oleate; sodium alkylaryl sulfonates; polyoxyethylene sulfates and phosphates; the ethyleneoxide condensate with long chain fatty acids, alcohols and mercaptansand the alkali metal salts of rosin acids. These materials andtechniques of employment of emulsion formation and maintenance are wellknown to the art and have no unusual application here. As they areconventional materials employed in a conventional manner furtherdescription is unnecessary.

The polymerization initiator is composed of one or more water-soluble,free-radial-generating species such as hydrogen peroxide or sodium,potassium, or ammonium persulfates, perborates, peracetates,percarbonates and the like. As is well known in the art, theseinitiators may be associated with activating systems such as redoxsystems which may incorporate mild reducing agents such as sulfites andthiosulfites and redox reaction promoters such as transition metal ions.

A chain transfer agent or mixture of chain transfer agents may be addedto the reaction medium to limit the molecular weight of the polymer.Such chain transfer agents are generally mercaptans such as dodecanethiol, pentane thiol, and butane thiol.

Those skilled in the art will be aware that other emulsifying agents,polymerization initiators and chain transfer agents may be used whencompatible with the polymerization system wherein employed.

The reaction may be carried out at temperatures from about 40 C. toabout 80 C., or at lower temperatures, as from C. to 80 C. in the caseof activated systems.

The graded rubber particles above described and this method ofpreparation are disclosed by Ray. A. Dickie and Seymour Newman in theirpatent application Ser. No. 100,464 filed of even date with thisapplication.

In another method of preparation, hereinafter illustrated, the rubberparticles are formed in an aliphatic hydrocarbon medium. in. VinylMonomers Employed l The Paint in The paint binder dispersionadvantageously contains about 20 to 80, preferably about 25 to about 75,weight percent vinyl monomers and about 20 to about 80, preferably about25 to about 75, weight percent of the polymeric component, i.e., thealpha-beta olefinically unsaturated, rubber-comprising resin formed byreacting the aforedescribed alpha-beta olefinically unsaturated,mono(acyl chloride)-functional polyester with the aforedescribedhydroxy-functional, acrylic, graded-rubber particle. Obviously, thepolymeric component may also contain other alpha-beta olefinicallyunsaturated resins such as those disclosed in U.S. Pat. Nos. 3,437,512;3,437,513; 3,437,514 and 3,509,234.

Monomer type and concentration provide one means for adjusting theviscosity of the paint dispersion to conform to the methods ofapplication desired, e.g., spray coating, roll coating, etc. Infunctional terms, the amount of vinyl monomer present is at leastsufficient to convert the alphabeta olefinically unsaturated,rubber-comprising resin into a cross-linked continuous coating on thesurface of a substrate when a film of such coating dispersion is exposedto ionizing radiation, e.g., electron beam.

Vinyl monomers employed may be monofunctional, monoacrylates formed bythe esterification of acrylic or methacrylic acid and a C -C preferablya C -C monohydric alcohol, e.g., methyl methacrylate, ethyl acrylate,buty] acrylate, butyl methacrylate, 2-ethyl hexyl acrylate, etc. Themonomer mixture may also include a minor amount, e.g., l to 30 molepercent, of diacrylates, e.g., the diesters of acrylic or methacrylicacid and a C C diol such as l,3-butylene diacrylate, 1,3-butylenebutylene dimethacrylate, 1,6-hexamethylene diacrylate, l,6-hexamethylenedimethacrylate, ethylene glycol dimethacrylate, etc.

Monovinyl hydrocarbons, e.g., styrene, alpha methyl styrene, vinyltoluene, etc., may also be used either alone or in combination with theaforementioned monoacrylates. Minor amounts, e.g., about I to about 30mole percent of the vinyl monomer mixture may be made up of divinylhydrocarbons such as divinyl benzene. Other vinyl monomers, e.g.,acrylonitrile, methacrylonitrile, vinyl acetate, etc, may be em ployedin minor amounts, e.g., about 1 to about 30 mole percent.

Advantageously, at least 70 weight percent of the vinyl monomercomponent is made up of monoacrylates selected from esters of a C Cmonohydric alcohol and acrylic or methacrylic acid and/or monovinylhydrocarbons having about eight to about nine carbon atoms. Frequently,it is advantageous to use a mixture of about 40 to about 60 mole percentof these monoacrylates and about 60 to about 40 mole percent of thesemonovinyl hydrocarbons.

IV. Preparation and Application Of The Coating Dispersion To A SubstrateBy adjusting the viscosity of the coating dispersion to a viscositycompatible with the desired method of coating, these coatings may beapplied by any of the conventional methods, e.g., brushing, spraying,roll coating, curtain coating, flow coating, etc.

The viscosity of the paint binder solution may be adjusted by varyingthe molecular weight of the alpha-beta olefinically unsaturated,rubber-comprising resin. This may be accomplished by controlling theaverage number of functional groups per graded-rubber particle bycontrolling the concentration of hydroxyl bearing monomer in the outershell, particularly in the final portion of the monomer mixtureintroduced into the reaction medium when the graded-rubber particle isproduced. The viscosity may also be regulated by varying the relativeconcentration of the resin component with respect to the vinyl monomercomponent and/or by varying the relative concentrations of dissimilarmonomers within the vinyl monomer component. The binder dispersion maybe applied to the substrate essentially free of nonpolymerizable,organic solvents and/or diluents or it may be applied with the solventand/or diluents in a method of application wherein the solvents and/ordiluents are flashed off prior to polymerizatron.

Coatings may be applied to any substrate, e.g., metal, wood, glass,polymeric solids, etc. These coatings will ordinarily be applied to anaverage depth in the range of about 0.1 to about 4 mils, more commonlyabout 05 about 2 mils.

V, Curing The Coatings Films formed of the paints of this invention canbe cured with ionizing radiation at relatively low temperatures, e.g.,room temperature (20 to 25 C.) or a temperature between room temperatureand that temperature at which significant vaporization of its mostvolatile component is initiated, ordinarily between 20 C. and 75 C. Theradiation energy is applied at dose rates of about 0.1 to about Mrad persecond on a workpiece, preferably a moving workpiece, with the coatingreceiving a total dose in the range of about I to about 25, commonlyabout 8 to about 15 Mrad.

The term ionizing radiation" as employed herein means radiation havingsufficient energy to remove an electron from a gas atom, forming an ion,hence radiation with minimum energy of, or equivalent to, at least about5,000 electron volts except when the curing is carried out in a vacuum.The preferred method of curing films of the instant paint binders on thesubstrates to which they have been applied is by subjecting such filmsto a beam of polymerization effecting electrons which at its source ofemission is within the range of, or equivalent to, about 100,000 toabout 500,000 electron volts. 1f irradiation is carried out in vacuum orat reduced pressure, this energy range may be considerably lower. Inthis method of curing, it is preferred to employ a minimum of about25,000 volts per inch of distance between the radiation emitter and theworkpiece where the intervening space is occupied by air or other gas ofcomparable density. Adjustment is made for the relative resistance ofthe intervening gas which is preferably an oxygen-free, inert gas suchas nitrogen or helium.

In this application, the term paint is meant to include finely groundpigment and/or filler in the binder, the binder without pigment and/orfiller or having very little of the same, which can be tinted, ifdesired. Thus, the binder, which is ultimately converted to a durablefilm resistant to wear, weather, etc., can be all or virtually all thatis used to form the film or it can be a vehicle for pigmentary and/ormineral filler material.

The abbreviation Mrad as employed herein means one million rad. The termrad as employed herein means that close of radiation which results inthe absorption of 100 ergs of energy per gram of absorber, i.e., coatingfilm. The electron emitting means may be a linear electron acceleratorcapable of producing a direct current potential in the rangehereinbefore mentioned. In such device, electrons are ordinarily emittedfrom a hot filament and accelerated through a uniform voltage gradient.The electron beam, which may be about one-eighth inch in diameter atthis point, is then scanned in one direction to make a fan-shaped beamand then passed through a metal window, e.g., aluminum, aluminumcopperalloy, or magnesium-thorium alloy of about 0.003 inch thickness. Thisinvention will be more fully understood from the following examples:

EXAMPLE 1 A. Preparation Of The Graded-Rubber Particle Graded rubberparticles are prepared in aqueous medium using the following procedures:To 1,000 parts by weight water which has been boiled and cooled to roomtemperature under a nitrogen atmosphere are added 2.86 parts by weightsodium dodecyl sulfate dissolved in 35.7 parts by weight water and aboutone-sixteenth of a monomer mixture consisting of 348 parts by weightbutyl acrylate and 32.3 parts by weight 1,3-butylene dimethacrylate. Themixture is stirred to establish dispersion of the monomers. To thestirred mixture are added 3. 14 parts by weight potassium persulfatedissolved in 71.4 parts by weight water and the mixture is heated to 45C. After about minutes addition of the remainder of the first monomermixture is begun at a rate such that the temperature of the reactionmixture is maintained at 47 to 49 C. The last half of the first monomermixture is added simultaneously with 2.86 parts by weight of sodiumdodecyl sulfate dissolved in 35.7 parts by weight water. Addition of thefirst monomer mixture requires about 45 minutes. The reaction mixture ismaintained at 47 to 49 C. for 35 minutes prior to beginning simultaneousdropwise addition ofa mixture of 236 parts by weight methylmethacrylate, 143.4 parts by weight glycidyl methacrylate, and 2.57parts by weight l-dodecane thiol and a solution of 5.72 parts by weightsodium dodecyl sulfate in 35.7 parts by weight water. This addition,which requires about 40 minutes, is carried out at such a rate that thetemperature of the reaction mixture is maintained at 48 to 49 C.Following this addition, the reaction mixture is maintained within thelast-mentioned temperature range for an additional 2 hours. Theresulting latex is cooled to room temperature and neutralized withaqueous ammonia. The overall conversion of monomers is about 98 percent.The size of these particles is found to be in the range of0.l to 0.2micron.

B. Determination of Epoxy Concentration Determination of theconcentration of the reactive epoxy groups on the shell of thegraded-rubber particles is made by the method involving addition oftetraethylammonium bromide followed by titration with perchloric acid inacetic acid using crystal violet as indicator. This method is describedby R. R. Jay in Analytical Chemistry, Vol. 36, page 667 (1964). C.Preparation Of Monohydroxy, Monocarboxy Terminated Unsaturated PolyesterA monohydroxy, monocarboxy terminated polyester is prepared in thefollowing manner: lO-hydroxydecanoic acid containing 0.5 weight percentof antimony trioxide is heated at for 3 hours under nitrogen and then 3hours in vacuo. The polyester thus formed has a molecular weight ofabout 2,500, a ratio of hydroxyl group to carboxyl group of unity, amelting point of about 78 C. and inherent viscosity of 0.25. Thedeterminations of hydroxyl groups, carboxyl groups and molecular weightare made by the method described by W. R. Sorenson and T. W. Campbell inPreparative Methods Of Polymer Chemistry," lnterscience Publishers, NewYork, New York, U.S.A. 1961 at page 134.

D. Reaction Of Monohydroxy, Monocarboxy Polyester With Acyl Chloride Thepolyester ofC is dissolved in chloroform and 1.0 weight percent ofpyridine is added. The temperature is raised to 60 C. and methacrylylchloride (20 percent excess over quantity required for completeconsumption of polyester hydroxyl groups) is added slowly over a periodof 2 hours. Heating is continued for an additional 2 hours and solventis removed under vacuum.

E. Reaction Of Alpha-Beta Olefinically Unsaturated, Monocarboxy]Terminated Polyester With Epoxy-Functional Graded-Rubber To a flaskequipped with stirrer, condenser, and nitrogen inlet are charged 1 molaramount of the epoxy-functional graded rubber particles (measured by 1mole of reactive epoxy groups on the surfaces thereof) 7 parts by weightof methyl methacrylate per each 3 parts by weight of epoxy-functionalgraded-rubber particles, the alpha-beta olefinically unsaturatedmonocarboxy terminated polyester of D in an amount that provides onecarboxyl group per each epoxy group on the graded-rubber chargedtherewith, i.e., 1 molar amount of the monocarboxy polyester, 1 weightpercent hyroquinone, and 1 weight percent triethylbenzylammoniumchloride (basis for last two items total weight of graded-rubber andpolyester in charge).

The mixture is warmed together at 60 C. for 8 hours.

The amount of methyl methacrylate monomer (or other acrylic monomers) isnot critical. Acrylic monomers act as solvent medium for this reaction.They are preferably used in an amount such that after reaction of thepolyester and graded-rubber the reaction mixture will possess thedesired viscosity for painting. If the concentration of monomers afterreaction is excessive, it may be removed by distillation under reducedpressure. If the concentration of monomers is deemed inadequate at thisstage, the desired viscosity can be achieved by adding monomers.

In this instance, the methyl methacrylate concentration is adjusted toprovide a paint binder dispersion containing 50 weight percent methylmethacrylate and 50 weight percent of the polymeric reaction product ofthe polyester and the graded-rubber particles.

F. Coating Of The Substrate This dispersion, which is now ready forpigmentation if desired, is applied to the substrate surfaces, i.e.,wood, metal, glass, and shaped polymeric solid(acrylonitrile-butadienestyrene copolymer), to the average depth ofabout 0.7 mil (0.0007 inch) and cured by exposure to electron beamirradiation. The conditions of irradiation are as follows:

Potential 275 kv, Current 30 ma. Distance emitter to workpiece K in.Dose 10-15 Mrad. Atmosphere nitrogen EXAMPLE 2 The procedure of ExampleI is repeated with the difference that an equimolar amount of acrylylchloride is substituted for the methyacrylyl chloride.

EXAMPLE 3 The procedure of Example 1 is repeated with the differencethat an equimolar amount of l2-hydroxydodecanoic acid is substituted forthe IO-hydroxydecanoic acid used in the preparation of the monohydroxy,monocarboxy terminated polyester.

EXAMPLE 4 The procedure of Example 1 is repeated with the differencethat equimolar amounts of IZ-hydroxystearic acid and 10- hydroxydecanoicacid are used in preparation of the monohydroxy, monocarboxy terminatedpolyester,

EXAMPLE 5 The procedure of Example 1 is repeated with the differencethat an equimolar amount of ricinoleic acid is substituted for theIO-hydroxydecanoic acid in preparation of the monohydroxy, monocarboxyterminated polyester.

EXA M PLE 6 The procedure of Example I is repeated with the differencethat a vinyl monomer mixture consisting of 2 molar parts methylmethacrylate, 1 molar part ethyl acrylate and 1 molar part Z-ethyl hexylacrylate is substituted for the methyl methacrylate component of thepaint.

EXAMPLE 7 The procedure of Example i is repeated with the differencethat a vinyl monomer mixture consisting of 2 molar parts methylmethacrylate, 1 molar part methyl styrene and 1 molar part butylacrylate is substituted for the methyl methacrylate component of thepaint.

EXAMPLE 8 The procedure of Example 1 is repeated with the differencethat a vinyl monomer mixture consisting of 2 molar parts styrene, 1molar part l,3-butylene dimethacrylate, and 1 molar part methylmethacrylate is substituted for the methyl methacrylate component of thepaint.

EXAMPLE 9 The procedure of Example 1 is repeated with the differencethat a vinyl monomer mixture consisting of 2 molar parts methylmethacrylate, 1 molar part styrene, and l molar part divinyl benzene issubstituted for the methyl methacrylate component of the paint.

EXAMPLE 10 The procedure of Example I is repeated with the differencethat a change is made in the composition of the epoxy-functionalgraded-rubber particles. The cores of the particles are here formed fromabout 85 mole percent butyl acrylate and about mole percent divinylbenzene, and the outer shells are here formed from a monomer mixtureconsisting essentially of 30 mole percent methyl methacrylate, 15 molepercent alpha methyl styrene, lO mole percent ethyl acrylate, 10 molepercent acrylonitrile, 10 mole percent methacrylonitrile, 10 molepercent butyl methacrylate, 5 mole percent vinyl acetate and 10 molepercent glycidyl acrylate, The monomers used to form the outer shellexcepting the glycidyl acrylate are divided into three portions. Afterthe first two portions are slowly added to the reaction mixture, thefinal portion is mixed with the glycidyl acrylate and added dropwise tothe reaction mixture.

EXAMPLE 1 l The procedure of Example 1 is repeated except for thepreparation of the epoxy-functional graded-rubber particles. The coresof the particles are here formed from about 90 mole percent ethylacrylate and about 10 mole percent of 1,1,1- trimethylolpropanetrimethacrylate.

EXAMPLE 12 The procedure of Example 1 is repeated except for thepreparation of the epoxy-functional graded-rubber particles. The coresof the particles are here formed from about 90 mole percent Z-ethylhexyl acrylate and about 10 mole percent of l ,4-dimethylolcyclohexanedimethacrylate.

EXAMPLE 13 The procedure of Example 1 is repeated except for thepreparation of the epoxy-functional graded-rubber particles. The coresof the particles are here formed from about 90 mole percent butylacrylate and about 10 mole percent divinyl benzene.

EXAMPLE 14 The procedure of Example I is repeated except for thedifference that the curing of the coatings upon the substrates iscarried out using an electron beam having an average potential ofabout260,000 electron volts.

EXAMPLE 15 The procedure of Example I is repeated except for thedifferences that the curing of the coatings upon the substrates iscarried out using a helium atmosphere and an electron beam having anaverage potential of about 150,000 electron volts.

EXAMPLE l6 The procedure of Example 1 is repeated except for thedifferences that the curing of the coatings upon the substrates iscarried out using an atmosphere comprising a major amount of nitrogenand a minor amount of carbon dioxide and a beam having an averagepotential of about 325,000 electron volts.

EXAMPLE 1? The procedure of Example 1 is repeated with the differencesthat the coating dispersion consists essentially of parts by weight ofthe alpha-beta olefinically unsaturated polyester and graded-rubberreaction product and about 20 parts by weight of vinyl monomers. Thevinyl monomers are a mixture of equimolar amounts of methyl methacrylateand styrene.

EXAMPLE 18 The procedure of Example 1 is repeated with the differencethat the coating dispersion consists essentially of 70 parts by weightof the alpha-beta olefmically unsaturated polyester and graded-rubberreaction product and about 30 parts by weight of vinyl monomers. Thevinyl monomers are a mixture of 30 mole percent methyl methacrylate, 20mole percent styrene, 20 mole percent ethyl acrylate, 10 mole percentacrylonitrile and 10 mole percent 1,3-butylene diacrylate.

EXAMPLE 19 The procedure of Example 1 is repeated with the differencethat the coating dispersion consists essentially of 20 parts by weightof the alpha-beta olefinically unsaturated polyester and graded-rubberreaction product and about 80 parts by weight of vinyl monomers. Thevinyl monomers are a mixture of mole percent methyl methacrylate andmole percent divinyl benzene.

EXAMPLE Materials Grams Ethyl Acrylate 80 l,3-butylene dimethacrylate 20Dispersing Agent 3 an amphipatic copolymer (one portion soluble in theacrylic monomers and the other portion soluble in the solvent, e.g.dodecane) is prepared by reacting l2- hydroxystearic acid (300 g.) inthe presence of stearyl alcohol (310 g.) and ptoluene sulfonic acid (6g.) at l80l90 C. until the acid value is less than l rngKOH/g. Theproduct is then reacted with methacrylic anhydride (170 g.). Theresulting material is then copolymerized with an e ual amount of methylmethacry late using AlBN initiator 9 g.) and but l acetate solvent. Thismethod ofproducing this dispensing agent is described in detail by K. E.J. Barratt and H. R. Thomas, Journal of Polymer Science, Part A I. Vol.7, 2625. (1969). Other dispersing agents which are effective forstabilizing suspensions in hydrocarbon liquids may be used in place ofthe ahove-described material. 2,2. azobis-(Z-methyl propionitrile).

Materials Grams Methyl Methacrylate 320 Glycidyl Methacrylate 88Dispersing Agent 3 AlBN 6 n-dodecane 1,000

Same as in A above.

EXAMPLE 21 The procedure of Example 1 is repeated except for thedifference that the polyester and graded-rubber reaction product isformed from 0.25 molar part of the alpha-beta olefinically unsaturated,monocarboxy terminated polyester and 1 molar part of theepoxy-functional graded rubber particles.

EXAMPLE 22 The procedure of Example 1 is repeated except for thedifference that the polyester and graded-rubber reaction product isformed from 0.5 molar part of the alpha-beta olefinically unsaturatedmonocarboxy terminated polyester and 1 molar part of theepoxy-functional graded-rubber particle.

The terms acrylate and acrylates, when used herein without a modifierdistinguishing between esters of acrylic acid and methacrylic acid,shall be understood to include both. This, of course, does not apply toa naming ofa specific compound.

It will be understood by those skilled in the art that modifications canbe made within the foregoing examples in the scope of this invention ashereinbefore described and hereinafter claimed.

We claim:

1. A radiation-curable paint which on a pigment and mineral filler-freebasis comprises a film-forming dispersion of about 80 to about 20 weightpercent vinyl monomers and about 20 to about 80 weight percent of apolymeric component consisting essentially of the product formed byreacting about 0.25 to 1 molar part of an alpha-beta olefinicallyunsaturated, monocarboxy terminated polyester with one molar part ofepoxy-functional particles of graded-rubber, said alpha-betaolefinically unsaturated, monocarboxy terminated polyester being formedby reacting a monohydroxy, monocarboxy terminated polyester with an acylchloride, said monohydroxy, monocarboxy terminated polyester having anaverage molecular weight in the range of 800 to 3,000 and 0.5 to about 5units of alpha-beta olefinic unsaturation per 1,000 units molecularweight, and having the chemical structure that is obtained bypolymerizing hydroxy acids having the formula wherein R and R may be Hor C to C alkyl and R is alkyl or aryl containing one to 20 carbonatoms, said molar part of epoxy-functional particles of graded-rubberbeing measured by and equivalent to one molar part of reactive epoxygroups on the surfaces thereof, said particles of graded-rubberconsisting essentially of 1 1. about 10 to about 90 weight percent of acore of crosslinked acrylic polymer consisting essentially of a. aboutto about 98 mole percent of a monoester of acrylic acid and a C Cmonohydric alcohol, and b. about 20 to about 2 mole percent of divinylbenzene, a diester of acrylic or methacrylic acid and a C C dihydricalcohol, or a triester of acrylic or methacrylic acid and a C Ctrihydric alcohol, and

2. about to about 10 weight percent of an outer shell consistingessentially of the polymerization product of monomer mixtures selectedfrom the group consisting of a. about 65 to about 98 mole percent methylmethacrylate and about 2 to about 35 mole percent of an epoxyfunctionalacrylate, and

b. about 2 to about 35 mole percent of an epoxy-functional acrylate andabout 65 to about 98 mole percent of a mixture consisting essentially ofesters of acrylic or methacrylic acid and a C,C monohydric alcohol, C -Cmonovinyl hydrocarbons, 0 to 30 mole percent of a difunctional compoundselected from divinyl benzene and diesters of acrylic or methacrylicacid and C C dihydric alcohol and O to 30 mole percent of a monomerselected from arcylonitrile, methacrylonitrile and vinyl acetate.

2. A paint in accordance with claim 1 wherein said core is cross-linkedacrylic polymer consisting essentially of butyl acrylate and adiacrylate selected from l,3-butylene diacrylate and 1,3 butylenedimethacrylate.

3. A paint in accordance with claim 1 wherein said core is cross-linkedacrylic polymer consisting essentially of Z-ethyl hexyl acrylate and adiacrylate selected from l,3-butylene diacrylate and l,3-butylenedimethacrylate.

4. A paint in accordance with claim 1 wherein said gradedrubberparticles have average diameter in the range of about 0.04 to about 1micron.

5. A paint in accordance with claim 1 wherein said major amount is about80 to about 98 mole percent and said minor and cross-linking amount isabout 2 to about 20 mole percent.

6. A paint in accordance with claim 1 wherein said vinyl monomers areselected from esters of acrylic acid and a C -C monohydric alcohol,esters of methacrylic acid and a C -C monohydric alcohol, C -C monovinylhydrocarbons, divinyl benzene, diesters of acrylic acid and a C -Cdihydric alcohol, and diesters of methacrylic acid and a C C dihydricalcohol.

7. A paint in accordance with claim 1 wherein said outer shell has glasstransition temperature at least 50 C. above that of said core.

8. The method of coating a substrate which comprises: (A) applying to asurface of said substrate a film of radiation-curable paint which on apigment and mineral filler-free basis comprises a film-formingdispersion of about 20 to about 80 weight percent of vinyl monomers andabout 80 to about 20 weight percent of a polymeric component formed byreacting about 0.25 to 1 molar part of an alpha-beta olefinicallyunsaturated, monocarboxy terminated polyester with one molar part ofepoxy-functional particles of graded-rubber, said alpha-betaolefinically unsaturated, monocarboxy terminated polyester being formedby reacting a monohydroxy, monocarboxy terminated polyester with an acylchloride, said monohydroxy, monocarboxy terminated polyester having anaverage molecular weight in the range of 800 to 3,000 and 0.5 to about 5units of alpha-beta olefinic unsaturation per 1,000 units molecularweight, and having the chemical structure that is obtained bypolymerizing hydroxy acids having the formula wherein R, and R may be Hor C, to C alkyl and R is alkyl or aryl containing one to 20 carbonatoms, said molar part of epoxy-functional particles of graded-rubberbeing measured by and equivalent to 1 molar part of reactive epoxygroups on the surfaces thereof, said particles of graded-rubberconsisting essentially of 1. about to about 90 weight percent of a coreof crosslinked acrylic polymer consisting essentially of a. about 80 toabout 98 mole percent ofa monoester of acrylic acid and a C' Cmonohydric alcohol, and

b. about to about 2 mole percent of divinyl benzene, a diester ofacrylic or methacrylic acid and a C C dihydric alcohol, or a triester ofacrylic or methacrylic acid and a C C trihydric alcohol, and

2 about 90 to about 10 weight percent of an outer shell consistingessentially of the polymerization product of monomer mixtures selectedfrom the group consisting of a. about 65 to about 98 mole percent methylmethacrylate and about 2 to about 35 mole percent of an epoxyfunctionalacrylate, and

b. about 2 to about 35 mole percent of an epoxy-functional acrylate andabout 65 to about 98 mole percent ofa mixture consisting essentially ofesters of acrylic or methacrylic acid and a C,C monohydric alcohol, C Cmonovinyl hydrocarbons, 0 to 30 mole percent of a difunctional compoundselected from divinyl benzene and diesters of acrylic or methacrylicacid and a C -C dihydric alcohol and 0 to 30 mole percent of a monomerselected from acrylonitrile, methacrylonitrile and vinyl acetate, and(B) cross-linking said film upon said substrate by exposing said film toa beam of electrons having average energy in the range of about 100,000to about 500,000 electron volts.

9. The method of claim 8 wherein said core is cross-linked acrylicpolymer consisting essentially of butyl acrylate and a diacrylateselected from 1,3 butylene diacrylate and 1,3 butylene dimethacrylate.

10. The method of claim 8 wherein said core is cross-linked acrylicpolymer consisting of 2-ethyl hexyl acrylate and a diacrylate selectedfrom 1,3 butylene diacrylate and 1,3 -butylene dimethacrylate.

1]. The method of claim 8 wherein said graded-rubber particles haveaverage diameter in the range of about 0. l to about 0.2 micron.

12. The method of claim 8 wherein said major amount is about 80 to about98 mole percent and said minor and crosslinking amount is about 2 toabout 20 mole percent.

13. The method of claim 8 wherein said vinyl monomers are selected fromesters of acrylic acid and a C -C monohydric alcohol, esters ofmethacrylic acid and a C -C monohydric alcohol, C -C monovinylhydrocarbons, divinyl benzene, diesters of acrylic acid and a C -Cdihydric alcohol, and diesters of methacrylic acid and a C C dihydricalcohol.

14. The method of claim 6 wherein sai outer shell has glass transitiontemperature at least 50 C. above that of said core.

15. An article of manufacture comprising in combination a substrate anda coating thereon comprising the polymerization product of afilm-forming dispersion cross-linked in situ by ionized radiation, saidfilm forming dispersion on a pigment and particulate filler-free basisconsisting essentially of about 20 to about weight percent vinylmonomers at least the major proportion of which are selected from estersof acrylic or methacrylic acid and a C -C monohydric alcohol and C -Cmonovinyl hydrocarbons and about 80 to about 20 weight percent of apolymeric component consisting essentially of the organic product formedby reacting about 025 to 1 molar part of an alpha-beta olefinicallyunsaturated, monocarboxy terminated polyester with one molar part ofepoxy-functional particles of graded-rubber, said alpha-betaolefinically unsaturated, monocarboxy terminated polyester being formedby reacting a monohydroxy, monocarboxy terminated polyester being formedby reacting a monohydroxy, monocarboxy terminated polyester with an acylchloride, said monohydroxy, monocarboxy terminated polyester having anaverage molecular weight in the range of 800 to 3,000 and 0.5 to about 5units of alpha-beta olefinic unsaturation per 1,000 units molecularweight, and having the chemical structure that is obtained bypolymerizing hydroxy acids having the formula OH Rz-Rr-COOH wherein R,and R may be H or C to C alkyl and R is alkyl or aryl containing one to20 carbon atoms, said molar part of epoxy-functional particles ofgraded-rubber being measured by and equivalent to one molar part ofreactive epoxy groups on the surfaces thereof, said particles ofgraded-rubber consisting essentially of l. about 10 to about weightpercent of a core of crosslinked acrylic polymer consisting essentiallyof a. about 80 to about 98 mole percent of a monoester of acrylic acidand a C -C monohydric alcohol, and b. about 20 to about 2 mole percentof divinyl benzene, a diester of acrylic or methacrylic acid and a C -Cdihydric alcohol, or a triester of acrylic or methacrylic acid and a C-C trihydric alcohol, and 2. an outer shell consisting essentially ofthe polymerization product of monomer mixtures selected from the groupconsisting of a. about 65 to about 98 mole percent methyl methacrylateand about 2 to about 35 mole percent of an epoxyfunctional acrylate, andb. about 2 to about 35 mole percent of an epoxy-functional acrylate andabout 65 to about 98 mole percent of a mixture consisting essentially ofesters of acrylic or methacrylic acid and a C,C monohydric alcohol, C,,Cmonovinyl hydrocarbons, 0 to 30 mole percent of a difunctional compoundselected from divinyl benzene and diesters of acrylic or methacrylicacid and C C dihydric alcohol and 0 to 30 mole percent of a monomerselected from acrylonitrile, methacrylonitrile and vinyl acetate.

2. about 90 to about 10 weight percent of an outer shell consistingessentially of the polymerization product of monomer mixtures selectedfrom the group consisting of a. about 65 to about 98 mole percent methylmethacrylate and about 2 to about 35 mole percent of an epoxy-functionalacrylate, and b. about 2 to about 35 mole percent of an epoxy-functionalacrylate and about 65 to about 98 mole percent of a mixture consistingessentially of esters of acrylic or methacrylic acid and a C1-C8monohydric alcohol, C8- C9 monovinyl hydrocarbons, 0 to 30 mole percentof a difunctional compound selected from divinyl benzene and diesters ofacrylic or methacrylic acid and C2-C6 dihydric alcohol and 0 to 30 molepercent of a monomer selected from arcylonitrile, methacrylonitrile andvinyl acetate.
 2. A paint in accordance with claim 1 wherein said coreis cross-linked acrylic polymer consisting essentially of butyl acrylateand a diacrylate selected from 1,3-butylene diacrylate and 1,3 -butylene dimethacrylate.
 2. an outer shell consisting essentially of thepolymerization product of monomer mixtures selected from the groupconsisting of a. about 65 to about 98 mole percent methyl methacrylateand about 2 to about 35 mole percent of an epoxy-functional acrylate,and b. about 2 to about 35 mole percent of an epoxy-functional acrylateand about 65 to about 98 mole percent of a mixture consistingessentially of esters of acrylic or methacrylic acid and a C1-C8monohydric alcohol, C8-C9 monovinyl hydrocarbons, 0 to 30 mole percentof a difunctional compound selected from divinyl benzene and diesters ofacrylic or methacrylic acid and C2-C6 dihydric alcohol and 0 to 30 molepercent of a monomer selected from acrylonitrile, methacrylonitrile andvinyl acetate.
 3. A paint in accordance with claim 1 wherein said coreis cross-linked acrylic polymer consisting essentially of 2-ethyl hexylacrylate and a diacrylate selected from 1,3-butylene diacrylate and1,3-butylene dimethacrylate.
 4. A paint in accordance with claim 1wherein said graded-rubber particles have average diameter in the rangeof about 0.04 to about 1 micron.
 5. A paint in accordance with claim 1wherein said major amount is about 80 to about 98 mole percent and saidminor and cross-linking amount is about 2 to about 20 mole percent.
 6. Apaint in accordance with claim 1 wherein said vinyl monomers areselected from esters of acrylic acid and a C1-C8 monohydric alcohol,esters of methacrylic acid and a C1-C8 monohydric alcohol, C8-C9monovinyl hydrocarbons, divinyl benzene, diesters of acrylic acid and aC2-C8 dihydric alcohol, and diesters of methacrylic acid and a C2-C8dihydric alcohol.
 7. A paint in accordance with claim 1 wherein saidouter shell has glass transition temperature at least 50* C. above thatof said core.
 8. The method of coating a substrate which comprises: (A)applying to a surface of said substrate a film of radiation-curablepaint which on a pigment and mineral filler-free basis comprises afilm-forming dispersion of about 20 to about 80 weight percent of vinylmonomers and about 80 to about 20 weight percent of a polymericcomponent formed by reacting about 0.25 to 1 molar part of an alpha-betaolefinically unsaturated, monocarboxy terminated polyester with onemolar part of epoxy-functional particles of graded-rubber, saidalpha-beta olefinically unsaturated, monocarboxy terminated polyesterbeing formed by reacting a monohydroxy, monocarboxy terminated polyesterwith an acyl chloride, said monohydroxy, monocarboxy terminatedpolyester having an average molecular weight in the range of 800 to3,000 and 0.5 to about 5 units of alpha-beta olefinic unsaturation per1,000 units molecular weight, and having the chemical structure that isobtained by polymerizing hydroxy acids having the formula wherein R1 andR2 may be H or C1 to C6 alkyl and R3 is alkyl or aryl containing one to20 carbon atoms, said molar part of epoxy-functional particles ofgraded-rubber being measured by and equivalent to 1 molar part ofreactive epoxy groups on the surfaces thereof, said particles ofgraded-rubber consisting essentially of
 9. The method of claim 8 whereinsaid core is cross-linked acrylic polymer consisting essentially ofbutyl acrylate and a diacrylate selected from 1,3 - butylene diacrylateand 1,3 -butylene dimethacrylate.
 10. The method of claim 8 wherein saidcore is cross-linked acrylic polymer consisting of 2-ethyl hexylacrylate and a diacrylate selected from 1,3 - butylene diacrylate and1,3 -butylene dimethacrylate.
 11. The method of claim 8 wherein saidgraded-rubber particles have average diameter in the range of about 0.1to about 0.2 micron.
 12. The method of claim 8 wherein said major amountis about 80 to about 98 mole percent and said minor and cross-linkingamount is about 2 to about 20 mole percent.
 13. The method of claim 8wherein said vinyl monomers are selected from esters of acrylic acid anda C1-C8 monohydric alcohol, esters of methacrylic acid and a C1-C8monohydric alcohol, C8-C9 monovinyl hydrocarbons, divinyl benzene,diesters of acrylic acid and a C2-C8 dihydric alcohol, and diesters ofmethacrylic acid and a C2-C8 dihydric alcohol.
 14. The method of claim 6wherein said outer shell has glass transition temperature at least 50*C. above that of said core.
 15. An article of manufacture comprising incombination a substrate and a coating thereon comprising thepolymerization product of a film-forming dispersion cross-linked in situby ionized radiation, said film forming dispersion on a pigment andparticulate filler-free basis consisting essentially of about 20 toabout 80 weight percent vinyl monomers at least the major proportion ofwhich are selected from esters of acrylic or methacrylic acid and aC1-C8 monohydric alcohol and C8-C9 monovinyl hydrocarbons and about 80to about 20 weight percent of a polymeric component consistingessentially of the organic product formed by reacting about 0.25 to 1molar part of an alpha-beta olefinically unsaturated, monocarboxyterminated polyester with one molar part of epoxy-functional particlesof graded-rubber, said alpha-beta olefinically unsaturated, monocarboxyterminated polyester being formed by reacting a monohydroxy, monocarboxyterminated polyester being formed by reacting a monohydroxy, monocarboxyterminated polyester with an acyl chloride, said monohydroxy,monocarboxy terminated polyester having an average molecular weight inthe range of 800 to 3,000 and 0.5 to about 5 units of alpha-betaolefinic unsaturation per 1,000 units molecular weight, and having thechemical structure that is obtained by polymerizing hydroxy acids havingthe formula wherein R1 and R2 may be H or C1 to C6 alkyl and R3 is alkylor aryl containing one to 20 carbon atoms, said molar part ofepoxy-functional particles of graded-rubber being measured by andequivalent to one molar part of reactive epoxy groups on the surfacesthereof, said particles of graded-rubber consisting essentially of